More than 200 million people travel to California each year to visit its many attractions. Outdoor enthusiasts enjoy the state's soaring mountains, whitewater rivers and sandy coastline, while others prefer the excitement of theme parks or relaxing in wine country vineyards. For a change of pace, head underground to view unusual limestone formations at one of the state's public caverns.

Sequoia National Park

Explore Boyden Caverns 74 miles east of Fresno in Sequoia National Park. Enjoy unique formations that have inspired cavern names such as the Pancake Room, Mother Nature’s Wedding Cake and the Drapery Room. Take a 45-minute walking tour or ramp up the adventure with a rappelling or canyoneering tour. Also in Sequoia, Crystal Cave is a half-mile hike from the parking area. Trailers, buses, and vehicles over 22 feet in length are not allowed on the narrow, twisting road. Leave strollers, walkers and hiking sticks behind. You’ll find the extra effort worth it when you reach the marble formations and underground stream. Five different tours are available, including a candlelit tour with lanterns. The cave is open from mid-May to November.

Sacramento Area

Black Chasm Caverns is a National Natural Landmark just 58 miles east of Sacramento. A 3,000-square-foot visitors center displays the caverns’ history and its connection to the Matrix Trilogy movies. Meander through the cave’s rare helictite formations on a 50-minute walking tour, or explore the forest surrounding the caverns on the three-hour Labyrinth Tour. Travel 39 miles south to arrive at California Caverns, where you can enjoy the splendor of the caverns on one of two walking tours lasting 50 to 80 minutes. For the spelunker, journey into the darkness while crawling and shimmying through cavern recesses on the Mammoth Cave and Middle Earth expeditions. Tours range from two to four hours.

Yosemite Area

Mercer and Moaning caverns lie just 7 miles apart, 50 miles northwest of Yosemite National Park’s west entrance. Mercer Caverns has been open to the public since the 1880s, when visitors used ropes and ladders to venture less than 1,000 feet inside while clutching candles attached to a board. Today’s modern 45-minute tour descends along more than 200 steps over a quarter-mile, which is similar to descending a 16-story building. Take a tour through the state’s largest vertical cavern at Moaning Caverns on a 45-minute walking tour. Thrill seekers enjoy a three-hour Adventure Trip that includes rappelling 165 feet into the main chamber. Above ground, a 32-foot climbing tower has routes for all skill levels, and zip lines rush up to 40 miles per hour through the trees.

Lake Shasta Caverns

Just 17 miles north of Redding, your visit to Lake Shasta Caverns begins with a ride on a 65-foot catamaran across the lake. A bus is waiting at the landing to whisk you uphill to the caverns’ entrance. Once underground, discover crystal formations that have formed over the ages. After the tour, check out the Rock Box where youngsters can test their climbing abilities on features that include a wall, tunnel, rock and oak tree house. Take a tour of the lake on a Catamaran or a World War II landing craft that was historically used to haul cattle in the area before the dam was built. Both boats include a licensed captain.